Cough is a most common symptom in internal medicine department and is found in a variety of respiratory and non-respiratory diseases. Cough itself is a defense mechanism for removing excess airway secretions and preventing foreign matters from being inhaled into the airway by mistake. However, the long-term cough may seriously influence the living quality of a patient and lead to high psychological burden to the patient and also obviously increase the personal and public medical and health expenditure.
According to the course of disease, the cough is classified into acute cough (less than 3 weeks), sub-acute cough (3-8 weeks) and chronic cough (more than or equal to 8 weeks). At present, the cough is generally treated by adopting central antitussive drug, peripheral antitussive drug, and expectorant and can generally achieve a good curative effect. However, there are still some acute and chronic coughs which cannot be relieved by adopting central antitussive drug such as codeine, resulting in conversion of acute cough into chronic cough; and moreover, the course of disease of the chronic cough patient can even reach several decades.
Many foreign epidemiological studies show that the incidence rate of chronic cough in the general population is about 9% to 33%. In 2003, a British epidemiological survey showed that the incidence rate of the chronic cough of the middle-aged people aged at 50 to 59 years reaches 12%; and the chronic cough patients accounted for about 20% of the respiratory disease outpatients. In recent years, along with the worsening of the air pollution (such as PM2.5, PM10, etc.), the incidence rate of the chronic cough is possible to increase continuously. The current study finds that main causes of the chronic cough include: cough variant asthma, eosinophilic bronchitis, gastroesophageal reflux cough and upper airway cough syndrome. The cough of a majority of patients may be obviously alleviated through the corresponding treatment according to the cough guideline for the cough caused by the above causes. However, there are still some patients with chronic cough having no obvious abnormalities after a series of comprehensive examination, but the cough symptoms persist, which is formerly known as chronic idiopathic cough (CIC); and the cough symptoms are not well alleviated and are not treated according to the causes of disease, which is the difficulty and key point in the chronic cough field at present. The study discovers that the chronic idiopathic cough is mostly found in the middle-aged people and is mostly caused by the cold, and the cough lasts for a long time; and moreover, the chronic idiopathic cough is abnormally sensitive to lampblack, pungent smells, cold air, cigarette smoke and the like, and the cough may be induced by laugh or talk sometimes, and it shows as obviously increased cough sensitivity. With regard to this situation, the chronic cough with increased cough sensitivity is named as cough hypersensitivity syndrome (CHS). The abnormal enhancement of the cough sensitivity is a common key characteristic of the CHS patients.
At present, there is no appropriate treatment means for the CHS patients to select. Most of the CHS patients are generally treated by virtue of antitussive drugs. However, the antitussive drugs such as codeine and dextromethorphan have different degrees of side effects such as constipation, sedation, respiratory depression, etc., thereby limiting its use; and moreover, some CHS patients even use the central antitussive drugs, but the cough still cannot be relieved and seriously influences the living quality of the patients in daily life.
The Fructus schisandrae is sour and sweet in taste and warm in nature. It manifests its therapeutic actions in the lung, heart and kidney meridians. Lung is a delicate organ and is averse to dryness, while the Fructus schisandrae is warm and moist and can moisten the lung to arrest cough; the chronic cough may cause the non-respiration of the kidney, while the Fructus schisandrae is sour and astringent and can help the kidney to improve the inspiration; and the effect of the Fructus schisandrae for treating the chronic cough caused by the deficiency of lung Yin and kidney Qi is great. It is recorded in “Natural Herb Collections” that: the consumptive cough should be treated by using the Schisandra chinensis (Turcz.) Baill., while the cold in the lung should be treated by using the Schisandra sphenanthera Rehd. et it is recorded in “YAOPINHUAYI” that: the Fructus schisandrae can astringe the Qi of lung and is mainly used to treat the consumptive chronic cough; and it is recorded in “Herb Sources” (BENCAOQIUYUAN) that: the Fructus schisandrae is an effective herb for treating the cough and can be used to treat cold cough, summer-heat-injured cough, dryness-causing cough, consumptive cough, renal water-deficiency cough, kidney heat deficiency cough, chronic cough and dyspnea. Zhang zhangjing clearly pointed out that all cough can be treated with the Fructus schisandrae. In “pharmacopoeia of the people's republic of china”, the Fructus schisandrae can be used to treat the chronic cough and dyspnea in deficiency condition and palpitation and insomnia, in the traditional Chinese medicine, the Fructus schisandrae is widely used to treat the dry cough without phlegm at the later period of the cough or the chronic lung-deficiency cough disease.
Main chemical components of the Fructus schisandrae are volatile oils, lignans, triterpenes, organic acids and polysaccharides, wherein dibenzocyclooctene lignans and nortriterpenoid lactones are representative components of the schisandra plant. The pharmacological activity of the Fructus schisandrae is wide; there are a lot of reports about the Fructus schisandrae; and particularly, there are a lot of studies on the use of the Fructus schisandrae in protecting the liver and calming the heart and soothing the nerves.
The polysaccharide component is an important component in Fructus schisandrae herb, and its content is about 10%. It is reported that the Fructus schisandrae total polysaccharides have functions for protecting the liver, improving the immunity, resisting the senility, resisting the fatigue, preventing tumors, lowering the lipid, losing weight, resisting the oxidation, etc. However, as a component with the largest content in Fructus schisandrae herb, the Fructus schisandrae total polysaccharides are not reported about the function for relieving the cough in the literature.